Forming large titanium parts has typically been done using a large heated press and matched die tooling. When parts to be formed are large (i.e., larger than 96 inches long), the die tooling is very expensive. The titanium itself is also very expensive, and current methods for forming large parts generally require relatively thick plates of titanium be used. For example, in the aircraft industry, titanium plates of up to 2.5 inches in thickness may be required to form a part with a final thickness of less than three quarter inches.
Further, current methods of fabricating large titanium parts typically require multiple machining operations and multiple stress relief procedures to avoid machining-induced stress or machining-released stresses that result in distortion of the end product. The multiple machining operations and multiple stress relieving procedures add many hours and much cost to the manufacturing process.
A method for forming large titanium parts according to the present disclosure allows large titanium parts to be formed from thin plates of titanium (0.75 inches thick, in one embodiment), and requires only one vacuum furnace sizing operation. In the preceding sentence, “thin” refers to plates with thicknesses significantly closer to the max thickness of the final product when compared to forgings and or hog outs from larger plates where the part form is machined into the part instead of formed into the part.
Using the method according to the present disclosure, a titanium plate is bent to form bends in the plate. The bent part is then roll-formed to form contours into the bent part. The surfaces of the contoured part are rough-machined, and the part is then secured to a bladed form fixture. The bladed form fixture comprises a plurality of header boards that secure the part to the fixture. The fixture part is placed in a thermal vacuum furnace and a stress-relieving operation is performed. The part is removed from the fixture and final machining is performed.